Core A functions to provide the leadership, interaction and co-ordination between the different projects of the PPG in order to facilitate them in meeting their scientific goals. It can be divided into two sections: scientific support and administrative support. Important functions of the scientific support will be: to organize and hold weekly meetings of the project leaders and key personnel, to hold executive meetings of the project leaders alone to review progress and scientific direction, and to hold annual reviews with an external advisory board to review progress on the overall goals of the PPG as a whole. Important aspects of administrative support will be to monitor the dispersion of financial resources, monitor research allocations. The steering committee composed of all four project leaders will meet twice a year to review expenditures and resource allocations for the projects and cores. The administrative core will also be responsible for writing and transmitting the yearly progress report on the PPG, including the written report of the External Advisory Committee. An additional function of the administrative core will be to disseminate a program for seminars at Stanford that are broadly related to the scientific directions of the PPG. A final aspect of the scientific support will be to ensure that all investigators are using common reagents and cell strains to maintain uniformity in experimental protocols.